/*
 * This is an OpenSSL-compatible implementation of the RSA Data Security, Inc.
 * MD5 Message-Digest Algorithm (RFC 1321).
 *
 * Homepage:
 * http://openwall.info/wiki/people/solar/software/public-domain-source-code/md5
 *
 * Author:
 * Alexander Peslyak, better known as Solar Designer <solar at openwall.com>
 *
 * This software was written by Alexander Peslyak in 2001.  No copyright is
 * claimed, and the software is hereby placed in the public domain.
 * In case this attempt to disclaim copyright and place the software in the
 * public domain is deemed null and void, then the software is
 * Copyright (c) 2001 Alexander Peslyak and it is hereby released to the
 * general public under the following terms:
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted.
 *
 * There's ABSOLUTELY NO WARRANTY, express or implied.
 *
 * (This is a heavily cut-down "BSD license".)
 *
 * This differs from Colin Plumb's older public domain implementation in that
 * no exactly 32-bit integer data type is required (any 32-bit or wider
 * unsigned integer data type will do), there's no compile-time endianness
 * configuration, and the function prototypes match OpenSSL's.  No code from
 * Colin Plumb's implementation has been reused; this comment merely compares
 * the properties of the two independent implementations.
 *
 * The primary goals of this implementation are portability and ease of use.
 * It is meant to be fast, but not as fast as possible.  Some known
 * optimizations are not included to reduce source code size and avoid
 * compile-time configuration.
 */

#define MD5_HASHBYTES 16

#include <string.h>

 /* Any 32-bit or wider unsigned integer data type will do */
typedef unsigned int MD5_u32plus;

typedef struct {
  MD5_u32plus lo, hi;
  MD5_u32plus a, b, c, d;
  unsigned char buffer[64];
  MD5_u32plus block[16];
} MD5_CTX;

static void MD5_Init(MD5_CTX *ctx);
static void MD5_Update(MD5_CTX *ctx, const void *data, unsigned long size);
static void MD5_Final(unsigned char *result, MD5_CTX *ctx);

/*
* The basic MD5 functions.
*
* F and G are optimized compared to their RFC 1321 definitions for
* architectures that lack an AND-NOT instruction, just like in Colin Plumb's
* implementation.
*/
#define F(x, y, z)			((z) ^ ((x) & ((y) ^ (z))))
#define G(x, y, z)			((y) ^ ((z) & ((x) ^ (y))))
#define H(x, y, z)			(((x) ^ (y)) ^ (z))
#define H2(x, y, z)			((x) ^ ((y) ^ (z)))
#define I(x, y, z)			((y) ^ ((x) | ~(z)))

/*
* The MD5 transformation for all four rounds.
*/
#define STEP(f, a, b, c, d, x, t, s) \
	(a) += f((b), (c), (d)) + (x) + (t); \
	(a) = (((a) << (s)) | (((a) & 0xffffffff) >> (32 - (s)))); \
	(a) += (b);

/*
* SET reads 4 input bytes in little-endian byte order and stores them
* in a properly aligned word in host byte order.
*
* The check for little-endian architectures that tolerate unaligned
* memory accesses is just an optimization.  Nothing will break if it
* doesn't work.
*/
#if defined(__i386__) || defined(__x86_64__) || defined(__vax__)
#define SET(n) \
	(*(MD5_u32plus *)&ptr[(n) * 4])
#define GET(n) \
	SET(n)
#else
#define SET(n) \
	(ctx->block[(n)] = \
	(MD5_u32plus)ptr[(n) * 4] | \
	((MD5_u32plus)ptr[(n) * 4 + 1] << 8) | \
	((MD5_u32plus)ptr[(n) * 4 + 2] << 16) | \
	((MD5_u32plus)ptr[(n) * 4 + 3] << 24))
#define GET(n) \
	(ctx->block[(n)])
#endif

/*
* This processes one or more 64-byte data blocks, but does NOT update
* the bit counters.  There are no alignment requirements.
*/
static const void *body(MD5_CTX *ctx, const void *data, unsigned long size)
{
  const unsigned char *ptr;
  MD5_u32plus a, b, c, d;
  MD5_u32plus saved_a, saved_b, saved_c, saved_d;

  ptr = (const unsigned char *)data;

  a = ctx->a;
  b = ctx->b;
  c = ctx->c;
  d = ctx->d;

  do {
    saved_a = a;
    saved_b = b;
    saved_c = c;
    saved_d = d;

    /* Round 1 */
    STEP(F, a, b, c, d, SET(0),  0xd76aa478, 7)
    STEP(F, d, a, b, c, SET(1),  0xe8c7b756, 12)
    STEP(F, c, d, a, b, SET(2),  0x242070db, 17)
    STEP(F, b, c, d, a, SET(3),  0xc1bdceee, 22)
    STEP(F, a, b, c, d, SET(4),  0xf57c0faf, 7)
    STEP(F, d, a, b, c, SET(5),  0x4787c62a, 12)
    STEP(F, c, d, a, b, SET(6),  0xa8304613, 17)
    STEP(F, b, c, d, a, SET(7),  0xfd469501, 22)
    STEP(F, a, b, c, d, SET(8),  0x698098d8, 7)
    STEP(F, d, a, b, c, SET(9),  0x8b44f7af, 12)
    STEP(F, c, d, a, b, SET(10), 0xffff5bb1, 17)
    STEP(F, b, c, d, a, SET(11), 0x895cd7be, 22)
    STEP(F, a, b, c, d, SET(12), 0x6b901122, 7)
    STEP(F, d, a, b, c, SET(13), 0xfd987193, 12)
    STEP(F, c, d, a, b, SET(14), 0xa679438e, 17)
    STEP(F, b, c, d, a, SET(15), 0x49b40821, 22)

    /* Round 2 */
    STEP(G, a, b, c, d, GET(1),  0xf61e2562, 5)
    STEP(G, d, a, b, c, GET(6),  0xc040b340, 9)
    STEP(G, c, d, a, b, GET(11), 0x265e5a51, 14)
    STEP(G, b, c, d, a, GET(0),  0xe9b6c7aa, 20)
    STEP(G, a, b, c, d, GET(5),  0xd62f105d, 5)
    STEP(G, d, a, b, c, GET(10), 0x02441453, 9)
    STEP(G, c, d, a, b, GET(15), 0xd8a1e681, 14)
    STEP(G, b, c, d, a, GET(4),  0xe7d3fbc8, 20)
    STEP(G, a, b, c, d, GET(9),  0x21e1cde6, 5)
    STEP(G, d, a, b, c, GET(14), 0xc33707d6, 9)
    STEP(G, c, d, a, b, GET(3),  0xf4d50d87, 14)
    STEP(G, b, c, d, a, GET(8),  0x455a14ed, 20)
    STEP(G, a, b, c, d, GET(13), 0xa9e3e905, 5)
    STEP(G, d, a, b, c, GET(2),  0xfcefa3f8, 9)
    STEP(G, c, d, a, b, GET(7),  0x676f02d9, 14)
    STEP(G, b, c, d, a, GET(12), 0x8d2a4c8a, 20)

    /* Round 3 */
    STEP(H,  a, b, c, d, GET(5),  0xfffa3942, 4)
    STEP(H2, d, a, b, c, GET(8),  0x8771f681, 11)
    STEP(H,  c, d, a, b, GET(11), 0x6d9d6122, 16)
    STEP(H2, b, c, d, a, GET(14), 0xfde5380c, 23)
    STEP(H,  a, b, c, d, GET(1),  0xa4beea44, 4)
    STEP(H2, d, a, b, c, GET(4),  0x4bdecfa9, 11)
    STEP(H,  c, d, a, b, GET(7),  0xf6bb4b60, 16)
    STEP(H2, b, c, d, a, GET(10), 0xbebfbc70, 23)
    STEP(H,  a, b, c, d, GET(13), 0x289b7ec6, 4)
    STEP(H2, d, a, b, c, GET(0),  0xeaa127fa, 11)
    STEP(H,  c, d, a, b, GET(3),  0xd4ef3085, 16)
    STEP(H2, b, c, d, a, GET(6),  0x04881d05, 23)
    STEP(H,  a, b, c, d, GET(9),  0xd9d4d039, 4)
    STEP(H2, d, a, b, c, GET(12), 0xe6db99e5, 11)
    STEP(H,  c, d, a, b, GET(15), 0x1fa27cf8, 16)
    STEP(H2, b, c, d, a, GET(2),  0xc4ac5665, 23)

    /* Round 4 */
    STEP(I, a, b, c, d, GET(0),  0xf4292244, 6)
    STEP(I, d, a, b, c, GET(7),  0x432aff97, 10)
    STEP(I, c, d, a, b, GET(14), 0xab9423a7, 15)
    STEP(I, b, c, d, a, GET(5),  0xfc93a039, 21)
    STEP(I, a, b, c, d, GET(12), 0x655b59c3, 6)
    STEP(I, d, a, b, c, GET(3),  0x8f0ccc92, 10)
    STEP(I, c, d, a, b, GET(10), 0xffeff47d, 15)
    STEP(I, b, c, d, a, GET(1),  0x85845dd1, 21)
    STEP(I, a, b, c, d, GET(8),  0x6fa87e4f, 6)
    STEP(I, d, a, b, c, GET(15), 0xfe2ce6e0, 10)
    STEP(I, c, d, a, b, GET(6),  0xa3014314, 15)
    STEP(I, b, c, d, a, GET(13), 0x4e0811a1, 21)
    STEP(I, a, b, c, d, GET(4),  0xf7537e82, 6)
    STEP(I, d, a, b, c, GET(11), 0xbd3af235, 10)
    STEP(I, c, d, a, b, GET(2),  0x2ad7d2bb, 15)
    STEP(I, b, c, d, a, GET(9),  0xeb86d391, 21)

    a += saved_a;
    b += saved_b;
    c += saved_c;
    d += saved_d;

    ptr += 64;
  } while (size -= 64);

  ctx->a = a;
  ctx->b = b;
  ctx->c = c;
  ctx->d = d;

  return ptr;
}

void MD5_Init(MD5_CTX *ctx)
{
  ctx->a = 0x67452301;
  ctx->b = 0xefcdab89;
  ctx->c = 0x98badcfe;
  ctx->d = 0x10325476;

  ctx->lo = 0;
  ctx->hi = 0;
}

void MD5_Update(MD5_CTX *ctx, const void *data, unsigned long size)
{
  MD5_u32plus saved_lo;
  unsigned long used, available;

  saved_lo = ctx->lo;
  if ((ctx->lo = (saved_lo + size) & 0x1fffffff) < saved_lo)
    ctx->hi++;
  ctx->hi += size >> 29;

  used = saved_lo & 0x3f;

  if (used) {
    available = 64 - used;

    if (size < available) {
      memcpy(&ctx->buffer[used], data, size);
      return;
    }

    memcpy(&ctx->buffer[used], data, available);
    data = (const unsigned char *)data + available;
    size -= available;
    body(ctx, ctx->buffer, 64);
  }

  if (size >= 64) {
    data = body(ctx, data, size & ~(unsigned long)0x3f);
    size &= 0x3f;
  }

  memcpy(ctx->buffer, data, size);
}

void MD5_Final(unsigned char *result, MD5_CTX *ctx)
{
  unsigned long used, available;

  used = ctx->lo & 0x3f;

  ctx->buffer[used++] = 0x80;

  available = 64 - used;

  if (available < 8) {
    memset(&ctx->buffer[used], 0, available);
    body(ctx, ctx->buffer, 64);
    used = 0;
    available = 64;
  }

  memset(&ctx->buffer[used], 0, available - 8);

  ctx->lo <<= 3;
  ctx->buffer[56] = ctx->lo;
  ctx->buffer[57] = ctx->lo >> 8;
  ctx->buffer[58] = ctx->lo >> 16;
  ctx->buffer[59] = ctx->lo >> 24;
  ctx->buffer[60] = ctx->hi;
  ctx->buffer[61] = ctx->hi >> 8;
  ctx->buffer[62] = ctx->hi >> 16;
  ctx->buffer[63] = ctx->hi >> 24;

  body(ctx, ctx->buffer, 64);

  result[0]  = ctx->a;
  result[1]  = ctx->a >> 8;
  result[2]  = ctx->a >> 16;
  result[3]  = ctx->a >> 24;
  result[4]  = ctx->b;
  result[5]  = ctx->b >> 8;
  result[6]  = ctx->b >> 16;
  result[7]  = ctx->b >> 24;
  result[8]  = ctx->c;
  result[9]  = ctx->c >> 8;
  result[10] = ctx->c >> 16;
  result[11] = ctx->c >> 24;
  result[12] = ctx->d;
  result[13] = ctx->d >> 8;
  result[14] = ctx->d >> 16;
  result[15] = ctx->d >> 24;

  memset(ctx, 0, sizeof(*ctx));
}
